Explanation
According to the Project Management Professional (PMP) Reference Materials, the next thing that the project manager should do when a client's company announces a reorganization, which includes changes in the senior management involved in the project, and the new project sponsor is asking to put the project on hold until they review the scope, is to discuss the requirements and update the project management plan with the new sponsor.
This is because the project sponsor is the person who provides the vision, direction, and resources for the project, and has the authority to approve or reject changes to the project scope, schedule, budget, and quality.
By discussing the requirements with the new sponsor, the project manager can ensure that the project aligns with the sponsor's expectations, goals, and priorities, and that the project scope is clearly defined and agreed upon. By updating the project management plan with the new sponsor, the project manager can reflect any changes or adjustments that may result from the reorganization or the scope review, and obtain the sponsor's approval and support for the project execution. Discussing the requirements and updating the project management plan with the new sponsor can help the project manager to establish a good relationship with the new sponsor, and ensure that the project delivers value to the client and meets the project objectives. References: Project Management Professional (PMP) Exam Content Outline, A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Seventh Edition, How to Create a Reorganization Plan in 4 Simple Steps, Steps in Managing a Reorganization.